Method and device for manufacturing bags from thin-walled tubular foil in a continuous process

ABSTRACT

A method and device for manufacturing bags for household refuse, starting from thin-walled synthetic tubular material, in which said material is tensioned upon the periphery of a drum, one or more combined cutting and sealing members being accommodated along said drum periphery.

United States Patent [191 Van Der Meulen 1 Oct. 2, 1973 METHOD AND DEVICE FOR MANUFACTURING BAGS FROM TI-IIN-WALLED TUBULAR FOIL IN A CONTINUOUS PROCESS [76] Inventor: Leonard Van Der Meulen, 30 D Maria de Molina, Madrid, Spain [22] Filed: Feb. 22, 1972 21 Appl. No.: 228,156

[30] Foreign Application Priority Data Feb. 23, I971 Netherlands ..71024l5 [52] US. Cl. 93/35 VL, 93/D1G. 1, 93/33 H, 93/84 TW [51] Int. Cl B31b 23/14, B31b 23/60 [58] Field of Search 93/33 H, DIG. 1, 93/35 R, 33 R, 26, 35 H, 84 TW, 35 VL [56] References Cited UNITED STATES PATENTS Nye et al. 93/DIG. 1

3,156,164 11/1964 Gassner 93/35 R X 2,775,171 12/1956 Steen et al...... 93/35 H X 2,737,859 3/1956 Allison et al.. 93/DIG. 1 3,509,799 5/1970 Weis et al. 93/35 R Primary Examiner-Andrew R. Juhasz Assistant Examiner-James F. Coan Att0rneyEric H. Waters et al.

[57] ABSTRACT A method and device for manufacturing bags for household refuse, starting from thin-walled synthetic tubular material, in which said material is tensioned upon the periphery of a drum, one or more combined cutting and sealing members being accommodated along said dt mipeipher 5 Claims, 2 Drawing Figures METHOD AND DEVICE FOR MANUFACTURING BAGS FROM THIN-WALLED TUBULAR FOIL IN A CONTINUOUS PROCESS BACKGROUND OF THE INVENTION My invention relates to a method for manufacturing in a continuous process, bags with a sealed bottom from thermoplastic tubular foil, the method comprising the steps of sealing and cutting through the tubular foil at regular intervals, in a direction transverse to its longitudinal sense and on the entire width of' the tube. Such a method is known in various versions but relates mostly to thick-walled sheet which can be easier handled than thin-walled foil. The treatment of thickwalled sheet requires on the other hand a rather extensive equipment-in connection with the substantial lapse of time which is necessary for sealing. This complication is superfluous in the case of thin-walled foil. It is therefore inefficient to. apply a method suitable for thick-walled sheet to thin-walled foil.

SUM-MARY OF THE INVENTION It is an object of my invention to provide a method which uses a short sealing time and which also allows for an adequate control of the material which is not so easily to be treated. To this end one feeds the tubular foil in a tangential direction to the outer circumference of a drum, while the drum rotates at a speed which at least is equal to the feeding velocity of the tube and in that one performs both a cut-through and a seal upon at least one location of the circumference of the drum.

Preferably the tangential velocity of the drum is greater than the rate at which the tubular foil is fed forward, the tubular foil being pressed on the outer circumference of the drum. As a result the thin-walled foil is pulled taught and as a consequence a better control of the consecutive operations is obtained.

My invention relates further to a device for manufacturing in a continuous process bags from thin-walled tubular foil, comprising a feeder for the foil, a surface supporting the foil and travelling therewith, at least one cutting member, and a sealing member, situated transverse to the direction of advance of the foil, the supportingsurface being constituted by the outer circumference of a drum and each cutting member being combined with a sealing member which is countersunk in the casing. of the drum. The circumference of the drum should be greater than the length of the bag to be manufactured and this curcumference should therefore be tuned to the size of the largest bag to be manufactured.

An important factor for successfully performing the method and applying the device according to my invention is constituted by the sealingmember which should be capable to manufacture an efficient seal in a very short time.

SURVEY OF THE DRAWINGS secutively folded twice in a longitudinal and'twice in a transverse direction;

FIG. 2 is a view of a detail from FIG. 1.

DESCRIPTION OF A PREFERRED EMBODIMENT According to FIG. 1 a frame 1 is provided in which a drum 2 and a first set of rollers 3 and 4' are mounted for rotation. The drive of the drum and of the rollers is effected in the direction of the arrows 5, 6 and 7. A feeder 8' for the uninterrupted supply of the tubular foil 9 is provided in the frame 1 and also a rotating cutting member 10 and some presser belts 11. Furthermore two conveyor belts 12 and 13' are provided serving for the discharge of the transversely folded bags.

Two folding blades (so-called knives) 14 are diametrically arranged in the drum 2. Furthermore two sealing members 15 are diametrically arranged in a countersunk position with respect to the outer circumference of the drum 2. These members comprise each two sealing jaws 16 which can open and close as will be further described with reference to FIG. 2. Near each sealing member 15 a resilient anvil 17 is provided which can co-operate with the cutting member 10. The roller 3 is provided with a clamping slit 18 and a knife 19. The roller 4 has a clamping slit 20. Arranged beside the cutting member 10 is a pusher member 21 consisting of some fingers 22 which can move from between the belts 11 for pressing the severed piece of tubular foil toward the countersunk sealing member 15. The drum 2 and the rollers 3 and 4 and the cutting member 10 are synchronized in such a way that the following conditions are satisfied:

The feeder 8 moves forward the tubular foil 9 at a rate which is smaller than the tangential velocity of the drum 2. The presser belts 11 move at the same rate as the circumference'of the drum. The cutting member It) performs two rotations against one rotation of the drum. Asa consequence two bags are made per revolution of the drum 2, the length of each bag being slightly smaller than half the circumference of the drum 2.

The rollers 3 and 4 rotate synchronously with the drum 2 in such a way that the clamping slit 18 cooperates consecutively with the two knives 14 of the drum 2, while per revolution the clamping slit 20 cooperates once with the knife 19. The method progressesas follows:

The tubular foil 9 is tangentially fed to the drum 2 and seized between the outer circumference of the drum and the belts 11 which both preferably move faster than the feeder 8. The thin-walled and very slack foil is pulledtaught because the feeder 8 determines the velocity of the foil. As soon as the anvil 17 is opposite the cuttingmember 10, the tubular foil is clamped thereinbetween and cut through over its full width so that a rectangular tubular length is severed from the advancingendless tubular foil. At this moment the trailing free end of this tubular foil length sinks into the drum, the pusher fingers 22 assisting the foil length so sink. Thereupon the sealing jaws 16 close whereby the transverse seal is formed and a bag is obtained which on one side is open. The folding knife 14 makes a first transverse fold approximately halfway the length of this bag at the moment that this knife starts co-operating with the clamping slit 18 of the roller 3. The fold made in this way engages the clamping slit 18. Since the drum 2 and the roller 3-continue to rotate in the direction of d the arrows 5 and 6, the bag, which for its lower half was already freely hanging, is pulled from the drum 2 and the clamping belt 11. In the depicted position this bag has already further advanced and the folding knife 19 of the roller 3 is already on the verge of starting its cooperation withthe now doubledbag. At the moment that this co-operationbecomes a fact the folding knife 19 puts the bag-into the clamping-slit 20, whereupon the bag provided now with two folds is conveyed further and delivered to the conveyor belts l2 and 13 which ensure that the bag is conveyed toward the left in FIG. 1. It should be noted that for each bag the fold which has just been made is at first offered to a next member providing for the further passage.

As is visible in FIG. 2 the two clamping jaws 16 are coupled to each other via gea r wheels 23, 24, with such a ratio of diameter that the outer clamping jaw described a greater arc than the inner one. An electric resistance wire (not depicted) is provided on both clamping jaws, current being supplied to the wires when the jaws are closed. In this way a two-sided welded joint of sufficient strength is obtained.

It should be noted that along the circumference of the drum 2 more than two sealing-cutting combinations 10, -17 may be provided. This depends on the size of the bag to be manufactured. On changing the size of the bag, one or two of these combinations can be made inoperative e.g., by retracting slightly the anvil 17 toward the center of the drum 2. The position of the folding knives 14 can be adjusted by turning the connecting arm 25.

Since the bags of thin tubular foil are handled with difficulty, they are preferably folded one or more times in a direction perpendicular to the transverse folds described hereinbefore. For that purpose the conveyor belts l2 and 13 are provided, which transfer the bag, which has been folded twice in a transverse direction, to a conveyor belt 26 which passes the bag between three drums 27, 28 and 29. These drums are rotatably supported in a frame 30 and are likewise provided with a folding knife and a clamping slit (not depicted). The effect of this part of the device is in conformity with the usual progress of operations with folding rollers (see Netherlands Patent Application No. 7,009,150).

It should be noted that the described embodiment relates to a machine for manufacturing folded bags. The invention is, however, not limited thereto, since the essence of the invention is in the first part of the method which relates to the cutting-through and the sealing of the bags on the drum. The bags manufactured in this manner may be directly discharged from the drum and transferred to a separate device for piling or folding.

The advantages of the invention can be summarized as follows:

the invention allows for the manufacture at a fast rate of thin-walled plastic bags, which bags one by one are very difficult to handle;

during the time that the bag remains on the outer circumference of the drum, a sufficient control can be exercised thereon for performing the cutting and sealing treatment.

I claim:

1. A method for the continuous manufacture of bags having a sealed bottom from continuously advanced thin-walled thermo-plastic tubular foil, the method comprising the steps of moving a supporting surface at a speed which is at least equal to the advancing velocity of the foil, feeding the tubular foil in the direction of movement of said surface so as to bring the foil into firm contact with said surface, cutting through the tubular foil at regular intervals in a direction transverse to its longitudinal direction of movement and across the entire width of the tube, pushing the trailing end of each cut-off length of the foil towards a pair of cooperative sealing means supported by and lying below said moving surface, and closing said sealing means so as to form a seal in said trailing end.

2. A method according to claim 1, comprising cutting said tubular foil with a revolving knife periodically cooperating with the moving supporting surface.

3. A device for manufacturing bags in a continuous process from thin-walled tubular foil, comprising a feeder for the foil, a surface supporting the foil and travelling therewith at a speed at least equal to the feeding speed of the foil, at least one movable cutting means being provided outside said surface, a resilient anvil on the travelling supporting surface adapted to cooperate with said cutting means, and at least one pair of sealing means extending transverse to the direction of travel of the supporting surface, and ahead of said anvil, each pair of said sealing means being countersunk in the travelling supporting surface, and a pusher being positioned near the cutting means adapted to urge the trailing end of the cut-off foil towards a pair of said sealing means.

4. A device according to claim 3, in which each pair of sealing means consists of two swingable clamping jaws adapted to be moved into openable and closed positions.

5. A device according to claim 3, comprising a plurality of pressing belts being provided along a part of the path of the travelling supporting surface, said pusher consisting of fingers being movable between the pressing belts. 

1. A method for the continuous manufacture of bags having a sealed bottom from continuously advanced thin-walled thermoplastic tubular foil, the method comprising the steps of moving a supporting surface at a speed which is at least equal to the advancing velocity of the foil, feeding the tubular foil in the direction of movement of said surface so as to bring the foil into firm contact with said surface, cutting through the tubular foil at regular intervals in a direction transverse to its longitudinal direction of movement and across the entire width of the tube, pushing the trailing end of each cut-off length of the foil towards a pair of cooperative sealing means supported by and lying below said moving surface, and closing said sealing means so as to form a seal in said trailing end.
 2. A method according to claim 1, comprising cutting said tubular foil with a revolving knife periodically co-operating with the moving supporting surface.
 3. A device for manufacturing bags in a continuous process from thin-walled tubular foil, comprising a feeder for the foil, a surface supporting the foil and travelling therewith at a speed at least equal to the feeding speed of the foil, at least one movable cutting means being provided outside said surface, a resilient anvil on the travelling supporting surface adapted to cooperate with said cutting means, and at least one pair of sealing means extending transverse to the direction of travel of the supporting surface, and ahead of said anvil, each pair of said sealing means being countersunk in the travelling supporting surface, and a pusher being positioned near the cutting means adapted to urge the trailing end of the cut-off foil Towards a pair of said sealing means.
 4. A device according to claim 3, in which each pair of sealing means consists of two swingable clamping jaws adapted to be moved into openable and closed positions.
 5. A device according to claim 3, comprising a plurality of pressing belts being provided along a part of the path of the travelling supporting surface, said pusher consisting of fingers being movable between the pressing belts. 